Heat open the season on top of NBA Power Rankings

The defending-champion Miami Heat hold top spot in the preseason edition of the TSN.ca NBA Power Rankings, but they have challengers lined up to knock them off their perch.

Last year's finalists, the San Antonio Spurs, are ranked second, ahead of the Indiana Pacers, a team that took Miami to the seventh game of the Eastern Conference Final.

After those two, the Heat's closest challengers last season, come the Brooklyn Nets and Los Angeles Clippers, two teams that made notable upgrades in the offseason. In the Nets' case, they plucked proven vets Kevin Garnett, Paul Pierce and Jason Terry from Boston, along with Andrei Kirilenko from Minnesota, to give them a much more formidable rotation.

In addition to a new coach, Doc Rivers, the Clippers brought in shooters J.J. Redick and Jared Dudley to spread the floor, ideally creating more room for Blake Griffin in the low post and giving Chris Paul more options as he runs the offence.

The Oklahoma City Thunder are ranked notably lower than might have been expected, at nine, because point guard Russell Westbrook is recovering from knee surgery.

As for Canada's entry, the Toronto Raptors are ranked 22nd, stuck between contending for a playoff spot and being bad enough to contend for one of the top picks in the 2014 Draft Lottery.